Abstract: A qubit device comprises first and second superconductor layers a capacitor, first and second interconnects. The first superconductor layer comprises a first c-axis perpendicular to covalently bound atomic layers. The second superconductor layer comprises a second c-axis perpendicular to covalently bound atomic layers. The first and second superconductor layers form a Josephson junction, wherein the first c-axis and the second c-axis are aligned with each other at the Josephson junction. The aligned first and second c-axes intersect both the first superconductor layer and the second superconductor layer. The capacitor comprises a first electrode and a second electrode. The first interconnect electrically connects the first electrode and the first superconductor layer. The second interconnect electrically connects the second electrode and the second superconductor layer.

Abstract: A superconducting device includes two nodes and a Josephson junction coupled between the two nodes, wherein the Josephson junction is characterized by a superconducting phase difference, ?, wherein the superconducting device has a potential that varies as a function of the superconducting phase difference, ?, and has a single potential well. The potential has a non-zero cubic term and quartic term is zero. The Josephson junction may be a single small Josephson junction. The superconducting device may include a superconducting ring connected between the two nodes. The superconducting ring may include a first ring portion with a plurality of large Josephson junctions connected in series. The superconducting ring may also include a second ring portion that includes the single small Josephson junction in parallel with the plurality of large Josephson junctions between the two nodes.

Abstract: A superconducting device includes two nodes and a Josephson junction coupled between the two nodes, wherein the Josephson junction is characterized by a superconducting phase difference, ?, wherein the superconducting device has a potential that varies as a function of the superconducting phase difference, ?, and has a single potential well. The potential has a non-zero cubic term and quartic term is zero. The Josephson junction may be a single small Josephson junction. The superconducting device may include a superconducting ring connected between the two nodes. The superconducting ring may include a first ring portion with a plurality of large Josephson junctions connected in series. The superconducting ring may also include a second ring portion that includes the single small Josephson junction in parallel with the plurality of large Josephson junctions between the two nodes.